Quiz study guides

You will receive a single score (0-4, see rubric) for each topic area representing your understanding of the course material in that area. A great way to study for quizzes in general is to (1) study the lecture notes and (2) quiz yourself with the labs.

1 Quiz 1

Quiz 1 will test the following learning objectives, divided into 6 topic areas. For each topic area, you should be able to do the list that follows. You can think of this as a studying checklist!

1. R Basics: general
   • Assign an object to a valid variable name, list all variables in the environment and remove them
   • Use packages and differentiate between installing and loading
   • Get help with a function or package from R
   • Return information about an object, including its structure, data type, length, and attributes
   • Explain what functions and control flow are; differentiate between types of control flow
2. R Basics: vectors, operations, and subsetting
   • Distinguish between an atomic vector and a list
   • Create atomic vectors and determine their data types
   • Differentiate between implicit and explicit coercion and coerce an object to another type
   • Use arithmetic, comparison, and logical operators on vectors
   • Explain how more complex data structures are built from atomic vectors and create them
   • Distinguish between NA and NULL
   • Subset vectors and higher dimensional objects with the [, [[ and $ operators
3. Data importing
   • Load the tidyverse, recognize the included packages, and critique code for redundant loading
   • Construct a tidy dataset and critique whether a given dataset is tidy
   • Use the map function from the purr package
   • Create a tibble and distinguish between a tibble and a data frame
   • Use readr to read delimited files and determine whether readr can read files of a given type
   • Use col_types to add a column specifications and explain how readr guesses without it
   • Solve the 3 most common importing problems we discussed in class
4. Data visualization: basics
   • Describe how to create a plot with ggplot2 including the 3 basic requirements
   • Distinguish between mapping and setting aesthetics
   • Describe how ggplot2 maps categorical variables to aesthetics and interpret the 3 common warnings people encounter in this process
   • Interpret ggplot() calls with explicit or implicit arguments for data and mapping
   • Recognize the geoms we discussed in class and select which to use for a given situation
   • Differentiate between globally and locally defined mappings and recognize them in given plot (or code)
5. Data visualization: layers
   • Use the position argument to modify the position of the geoms in geom_bar() or geom_point()
   • Describe stat="identity" and describe the default transformations for geom_bar(), geom_histogram(), and geom_smooth()
   • Set the smoothing method for geom_smooth() and the bins or bindwidth for geom_histogram()
   • Facet a plot with facet_wrap() and facet_grid()
   • Modify axis, legend, and plot labels with labs()
   • Apply a given theme to a plot and adjust the base font size or family.
   • Describe scales and recognize the outcome of adding a scale layer
6. Data wrangling
   • Describe the common structure of dplyr functions (aka verbs)
   • Combine dplyr functions with the pipe operator to solve complex problems
   • Manipulate rows with filter(), arrange(), and distinct()
   • Maniuplate columns with mutate(), select(), and rename()
   • Group and summarise data with group_by(), summarise(), and ungroup()
   • Evaulate dplyr functions that include the common arguments we covered in class

2 Quiz 2

Quiz 2 will test the following learning objectives, divided into 3 topic areas. For each topic area, you should be able to do the list that follows. You can think of this as a studying checklist!

1. Sampling distribution
   • Explore a dataset with an appropriate figure (histogram, boxplot, scatterplot) and summary statistics appropriate for the distribution.
   • Recognize uniform and Gaussian probability distributions in a plot or equation and use R’s functions d*(), p*(), and r*() to work with these distributions
   • Explain the difference between the parameter and the paramter estimate
   • Construct the sampling distribution of a paramater estimate with infer and quantify the spread of the distribution with a confidence interval.
2. Hypothesis testing
   • Given a set of data, implement the 3-step hypothesis testing framework nonparametrically: (1) Pose a null hypothesis, (2) quantify how likely a given pattern of results is under the null, and (3) determine whether to reject the null (conceptually and with the infer framework).
   • Given a theoretical distriubiton (e.g. t), implement the 3-step hypothesis testing framework parametrically.
   • Given an observed correlation, determine whether a correlation is positive, negative, or no correlation.
   • Explain correlation as model building
3. Model specification
   • Classify a model as supervised or unsupervised, regression or classification, and linear or nonlinear
   • Identify the response and explanatory variables from a given research question or model
   • Recognize the 4 ways of writing the linear model equation
   • Select the equation (e.g \(y = \beta_0 + \beta_1x_1 + \beta_2x_2\)) or R expression (e.g. y ~ year + gender) for a plotted model